It is known that conventional spam and virus filters can block email from entering a network based on spam attributes. It is known that conventional email systems can recall email sent from one client to a second client of the same server. Referring now to the figures, it is known that circuits may be embodied as processors controlled by software encoded on computer readable media. FIG. 1 illustrates a non-limiting exemplary processor adapted to perform the operation of circuits described below.
FIG. 2 is a block diagram illustration of elements in a conventional email system. FIG. 2 shows an email client 240 coupled to a local area network 210 which connects the email client to an email server 220. Email client 240 sends an email addressed to a recipient at email client 250.
FIG. 3 is a block diagram illustration of one embodiment of a conventional email system. FIG. 3 shows mailboxes 222 coupled to email server 220. Each email for email client 250 is stored into an email store attached to the email server. When a client reads mail it will access its mailboxes through the local area network.
FIG. 4 is a block diagram illustration of another embodiment of a conventional email system. FIG. 4 shows email client 250 coupled to a local store for mailboxes 252. In an embodiment, email server 220 pushes email to email client 250 and stores into email client 250's mailboxes 252.
FIG. 5 is a block diagram illustration of a hybrid embodiment of a conventional email system. FIG. 5 shows both an email server attached store for mailboxes 222 as well as a client attached store for mailboxes 252. In an embodiment, mail is stored in duplicate at both the email server and at the email client. Also it is known that an email client may recall a email sent to another client on the same conventional email server.
FIG. 6 is a block diagram illustration of a conventional email system attached to a wide area network 310 such as the Internet. Email senders 320 coupled to the wide area network 310 may send email to email clients 240 and 250 through email server 220. Such emails are not recallable. Such emails frequently include undesirable emails called spam.
FIG. 7 is a block diagram illustration of a conventional email system with an anti-spam appliance installed. In FIG. 7, a spam filter 430 connects to an external spam reference library 420 to request an update to its anti-spam software.
FIG. 8 is a block diagram illustration of a conventional email system with anti-spam functionality. If a message sent by email senders 320 is not recognized by the anti-spam software update most recently updated from the spam reference library 420 it is forwarded to the email server 220 and thence to mailboxes either 222 or 252 or both.
Spammer senders have determined to modify their spam mail quicker than spam reference libraries can update and distribute their anti-spam software. By controlling large numbers of hijacked robots, a large volume of spam may be sent in a few hours or days.
Thus it can be appreciated that what is needed is a way to apply anti-spam software to email which has already passed through a spam filter into client mailboxes.